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The application of heteroatom doped cobalt (Ni@Co/C) prepared from a porous metal–organic framework as the cathode material for the rechargeable zinc–air batteries has been demonstrated. The Ni@Co/C‐modified electrode showed an excellent catalytic activity toward oxidation–reduction reaction and oxygen evolution reactions. The Co/C catalysts, which were Co particle impregnated on graphitic carbon powders, were synthesized after the calcination of Co3 (SDA)3(DMF)2 precursor, and then Ni deposition (Ni@Co/C) was followed on it by chemical reduction. Linear sweep voltammetry measurement indicates that Ni@Co/C‐H800, which had Ni particles on Co/C derived from MOF at 800 °C under N2, exhibited excellent performance. The stable charging/discharging profiles at 20 mA cm−2 of current were obtained for the 350 h in alkaline medium, suggesting Ni@Co/C‐H800 as a potential candidate for oxidation–reduction and evolution reactions. [ABSTRACT FROM AUTHOR]

A metal–organic framework (MOF) was synthesized using 4,4′‐stilbenedicarboxylic acid (H2SDA) in dimethylformamide (DMF). Carbon‐coated Co (C@Co) catalysts were prepared by the direct calcination of Co3(SDA)3(DMF)2 MOF crystals at various temperatures. The highest surface area of the C@Co catalyst is obtained at 600 °C which can further be increased by the ball mill operation. The X‐ray photon spectroscopy and X‐ray diffraction analysis proved the formation of metallic Co in the carbon matrix at temperatures over 500 °C, while Co3O4 formation was observed at 500 °C. Furthermore, the graphitic properties of the Co particles were analyzed by Raman spectroscopy. The durability of the carbon‐coated Co catalysts derived from MOFs (C@Co catalysts) was analyzed by the cycle test (charge/discharge at 20 mA/cm2 per 2 h) and was retained over 350 h. These catalysts showed remarkable stability for both ORR (oxygen reduction reaction) and OER (oxygen evolution reaction), comparable to that of Co3O4 and Co metal powder in alkaline solution. [ABSTRACT FROM AUTHOR]

[Display omitted] • Fabrication of nickel-cobalt nanocage for oxygen evolution reactions. • Excellent oxygen evolution reaction performance with overpotential of 350 mV. • Synergic effect of cobalt-nickel catalyst improves the conductivity and charge transfer. The development of efficient, eco-friendly, and inexpensive electrocatalysts has become crucial and significant in water-splitting applications. Herein, we developed a nickel-cobalt nanocage (Ni/Co-NC) electrocatalyst via the solvothermal method which can boost the performances towards oxygen evolution reactions (OER) and hydrogen evolution reactions (HER). The Ni/Co-NC reveals significant performance at an onset potential of 350 mV for the OER at a delivered current density of 10 mA cm−2. The significant amount of oxygen vacancies generated by the addition of nickel in cobalt has been verified by XPS and the nanocage structure revealed by TEM and SEM images helps in effective performance for OER/HER. Furthermore, the synergistic effect between various Ni3+/Ni2+ and Co2+ could optimize the performance resulting in a smaller Tafel slope of 70 mV dec−1 for Ni/Co-NC. [ABSTRACT FROM AUTHOR]

The wide structural versatility of the Metal-Organic Framework (MOF) is considered to be potential catalysts. In this work, [Mn (BDC). nDMF] n was synthesized by the reaction of 1,4-benzene dicarboxylic acid (1,4-BDC) with Manganese (II) nitrate using a solvothermal method. The [Mn (BDC). nDMF] n crystals were calcined for 2 h to produce Mn-MOF derived catalysts (C@MnO catalysts). The formation of MnO crystals was investigated by the X-ray diffraction (XRD) and the Raman Spectroscopy analyzed the graphitization. The resulting catalysts, C@MnO are highly porous with a high specific surface area of 291.62 m2/g at 700 °C. After calcination, Ni deposition was performed, to produce Ni@C@MnO on which Ni-atoms are deposited on the surface of MnO. The surface area reduces to 214.09 m2/g at 700 °C and the structure is distorted due to deposition. Numerous characterization techniques, including XRD, SEM, EDS, TGA, and Raman, strongly support the effective incorporation of Mn and Ni into the material frameworks. When applied as a cathode for Zinc-air battery, the Ni@C@MnO electrode delivered a high current density of 0.206 Acm−2 for the OER. The cyclic test for charging-discharging was performed for 152 cycles revealing a potential catalyst, having splendid stability for the OER and ORR. Unlabelled Image • Fabrication of carbon-coated manganese (C@MnO) catalysts by solvothermal method • Nickel deposition on C@MnO catalysts • Improved catalytic performance for the oxygen reduction and evolution reactions [ABSTRACT FROM AUTHOR]

• Fabrication of efficient bimetallic catalysts for OER. • Nickel decoration was performed on bimetallic CNT/CoNi. • Ni/CNT/CoNi exhibited excellent electrochemical performance and cycling stability. The fabrication of efficient catalysts for the oxygen evolution reactions (OER) that are required to accelerate the sluggish kinetics of metal-air batteries has attracted significant attention for application in energy conversion devices. Metal-organic frameworks (MOFs) have been recognized as potential candidates for the formation of promising catalysts. In this study, we report the formation of Ni/CNT/CoNi using bimetallic-ZIF (CoNi-ZIF) as a precursor. Bimetallic CoNi encapsulated in carbon nanotubes (CNTs) was obtained by calcinating CoNi-ZIF-67 to yield CNT/CoNi. The resulting CNT/CoNi was highly porous with a significant specific surface area of 242 m2/g. After calcination, Ni deposition on the CNT was performed and the surface area was reduced to 168.7 m2/g. Ni/CNT/CoNi was applied as a cathode material in zinc-air batteries, exhibiting excellent electrochemical performance and cycling stability. [ABSTRACT FROM AUTHOR]